I just stumbled across this and decided to compare Jake's "million" example (after fixing a few code typos) with "quick and dirty" stuff I have run (and found virtually no difference among the methods).

On a Dell9100 running 3GHz dual core and 2GzRAM (+ ~ 50 background processes):
Double Quotes: 0.327
vbNullString: 0.327
Len: 0.329

not much difference